Exemplary embodiments herein relate to a mounting structure, and more particularly to frame mounting structures for vehicles.
As new vehicles are being developed, there is an increased desire to improve their fuel efficiency. One way to accomplish this goal is to reduce the overall weight of the vehicle. As the curb weight of the vehicle is largely comprised of the frame mounting structure, there are numerous opportunities to reduce the curb weight by improving the frame structure. However, these improvements to the frame assembly should not adversely affect the handling or performance of the vehicle.
A conventional vehicle frame assembly is shown in FIG. 1. The vehicle frame assembly 10 includes a frame member 12 that supports a vehicle body and a subframe 16 that could support a vehicle engine, transmission, or suspension component. The frame member 12 and the subframe 16 are joined together by placing the subframe 16 between the frame member 12 and a bolt stay 26. A first fastener 18 extends through the bolt stay 26, the subframe 16, and into the frame member 12. The first fastener 18 provides attachment between the frame member 12 and the subframe 16.
Further, a bushing 20 is coaxially disposed on the first fastener 18 with an upper bushing stopper 22 and a lower bushing stopper 24 surrounding the bushing 20. A second fastener 28 attaches the bolt stay 26 to the frame member 12. Finally, the frame member 12 defines a neutral axis 14. The neutral axis 14 is an axis in which there are no longitudinal stresses or strains. The greater the distance between the neutral axis and the attachment point of the subframe to the structural member, the larger the moment arm will be. It is desirable to minimize the length L between the neutral axis 14 and the subframe 16. By minimizing the distance L, handling of the vehicle can be better controlled.
Because of the layout of the traditional frame assembly 10, the bushing stoppers 22, 24 are positioned horizontally. Thus, the bushing stoppers 22, 24 are preloaded by the vehicle weight, thereby degrading vehicle handling. Further, the bolt stay 26 of the frame assembly 10 is used for stiffness purposes. The presence of the bolt stay 26 contributes to the curb weight. Additionally, because of the positioning of the bolt stay 26, it is only effective in one direction. Specifically, the bolt stay 26 is only effective in either the lateral or longitudinal direction. Thus, the handling of a vehicle with the traditional frame assembly 10 suffers.